[otns] add default (weak) OTNS platform API implementation in core (#12308)

A default OTNS platform API function otPlatOtnsStatus() is now
provided that writes the status push to the log always (regardless of
configured log level). This is useful as a default handling for apps
built with -DOT_OTNS=ON, avoiding linker errors while not mandating
each platform to implement the API by itself.

Specifically it enables the Posix CLI app ot-cli to be built with OTNS
support, which is required to run Posix nodes in OTNS and receive the
status-push events via stdout logging.

The logging is emitted from the module named "Otns" so that a
simulator or other tool can easily detect the OTNS format status push
events in the log output.

examples/platforms/simulation/misc.c

@@ -122,7 +122,3 @@ void otPlatAssertFail(const char *aFilename, int aLineNumber)
     assert(false);
     exit(1);
 }
-
-#if OPENTHREAD_CONFIG_OTNS_ENABLE && !OPENTHREAD_SIMULATION_VIRTUAL_TIME
-void otPlatOtnsStatus(const char *aStatus) { OT_UNUSED_VARIABLE(aStatus); }
-#endif

examples/platforms/utils/CMakeLists.txt

@@ -31,7 +31,6 @@ add_library(openthread-platform-utils OBJECT
     link_metrics.cpp
     logging_rtt.c
     mac_frame.cpp
-    otns_utils.cpp
     settings_ram.c
     soft_source_match_table.c
     uart_rtt.c

examples/platforms/utils/otns_utils.cpp

@@ -1,52 +0,0 @@
-/*
- *  Copyright (c) 2020, The OpenThread Authors.
- *  All rights reserved.
- *
- *  Redistribution and use in source and binary forms, with or without
- *  modification, are permitted provided that the following conditions are met:
- *  1. Redistributions of source code must retain the above copyright
- *     notice, this list of conditions and the following disclaimer.
- *  2. Redistributions in binary form must reproduce the above copyright
- *     notice, this list of conditions and the following disclaimer in the
- *     documentation and/or other materials provided with the distribution.
- *  3. Neither the name of the copyright holder nor the
- *     names of its contributors may be used to endorse or promote products
- *     derived from this software without specific prior written permission.
- *
- *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
- *  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- *  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- *  ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
- *  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
- *  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
- *  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
- *  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
- *  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
- *  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
- *  POSSIBILITY OF SUCH DAMAGE.
- */
-#include <openthread-core-config.h>
-#include <openthread/config.h>
-
-#include <openthread/platform/otns.h>
-#include <openthread/platform/toolchain.h>
-
-#include "common/log.hpp"
-
-using namespace ot;
-
-/*
- * Implementation note:
- *   These are all "weak" so that a platform may if it chooses to override the instance.
- */
-
-#if OPENTHREAD_CONFIG_OTNS_ENABLE
-
-OT_TOOL_WEAK
-void otPlatOtnsStatus(const char *aStatus)
-{
-    OT_UNUSED_VARIABLE(aStatus);
-    LogAlways("[OTNS] %s", aStatus);
-}
-
-#endif // OPENTHREAD_CONFIG_OTNS_ENABLE

src/core/utils/otns.cpp

@@ -220,6 +220,15 @@ exit:
 }
 #endif // OPENTHREAD_MTD || OPENTHREAD_FTD
 
+//---------------------------------------------------------------------------------------------------------------------
+// Default/weak implementation of OTNS platform APIs
+
+extern "C" OT_TOOL_WEAK void otPlatOtnsStatus(const char *aStatus)
+{
+    OT_UNUSED_VARIABLE(aStatus);
+    LogAt(kLogLevelNone, "%s", aStatus);
+}
+
 } // namespace Utils
 } // namespace ot
 

tests/gtest/fake_platform.cpp

@@ -666,9 +666,5 @@ void otPlatDnssdStartRecordQuerier(otInstance *, const otPlatDnssdRecordQuerier
 
 void otPlatDnssdStopRecordQuerier(otInstance *, const otPlatDnssdRecordQuerier *) {}
 
-#if OPENTHREAD_CONFIG_OTNS_ENABLE
-void otPlatOtnsStatus(const char *aStatus) { OT_UNUSED_VARIABLE(aStatus); }
-#endif
-
 void otPlatAssertFail(const char *, int) {}
 } // extern "C"

tests/unit/test_platform.cpp

@@ -441,10 +441,6 @@ OT_TOOL_WEAK uint8_t otPlatRadioGetCslAccuracy(otInstance *)
 }
 #endif
 
-#if OPENTHREAD_CONFIG_OTNS_ENABLE
-OT_TOOL_WEAK void otPlatOtnsStatus(const char *) {}
-#endif
-
 #if OPENTHREAD_CONFIG_RADIO_LINK_TREL_ENABLE
 OT_TOOL_WEAK void otPlatTrelEnable(otInstance *, uint16_t *) {}